(1) Field of the Invention
This invention is concerned with the treatment of articles, e.g. shoe parts, having a coating of a moisture-curable composition, more particularly an apparatus for the treatment of such articles comprising a support for an article to be treated, a chamber for receiving the support, an article treatment means for supplying heat and moisture to the chamber thus to treat an article supported therein.
(2) Prior Art
Apparatus for the treatment of articles other than shoe parts, e.g. printed material, are known, such apparatus usually comprising a chamber in the form of a tunnel through which an article supported on a support can be progressively moved, heat and moisture being supplied to the chamber. Such an apparatus is customarily connected to a printing machine by means of a feed device which feeds printed articles successively into the chamber, the articles then passing through the chamber at a relatively slow rate and being treated during such passage. Because of the successive presentation of articles automatically, usually the tunnel is open at both ends and the article treatment means is located along a central part of the tunnel.
Apparatus for the treatment of shoe parts (but not having a coating of a moisture-curable composition) of the aforementioned type is also well known, namely so-called heat setting apparatus, in which shoes on lasts are passed progressively through a tunnel and subjected to heat and moisture during such passage so that the shoe upper is caused to conform to the shape of the last and to retain such form in the finished shoe. Again, the passage of the articles through the tunnel is relatively slow.
There has been proposed in U.K. Patent Specification No. 1540634 a method of bonding a shoe sole to a shoe upper using selected urethane prepolymer compositions which are provided as fluid compositions and which are convertible, by a chain extension treatment (by curing), to a polyurethane which, when heated, is tacky and capable of establishing a substantially immediate strong adhesive union with a compatible adhesive or resin surface. The curing of the composition preferably takes place by the application of heat and moisture. More recently, furthermore, an adhesive suitable for use in carrying out such a method, and identified as "Bostik
5102" ("Bostik" is a Registered Trade Mark), has become available.
In carrying out such a method, however, in the manufacture of shoes, it is desirable that the curing of the composition takes place relatively rapidly. This is beneficial not only in that the space requirement for a machine through which the shoe parts progress slowly is relatively large, but also in that the slower the curing process, the greater the number of parts which at any given time are in the course of curing, with consequent disadvantages, e.g. in the use of labour towards the end of a working shift and also problems of storing coated parts between shifts. Consequently, the known type of apparatus referred to above cannot satisfactorily be used.
Furthermore, in the known apparatus referred to above, no further operation is contingent upon the particular treatment step carried out in such apparatus. Thus, in the case of printed material, once it is dried it constitutes the finished product, and similarly in the case of a heat setting apparatus no further shoe-making operation is dependent upon the degree of heat set produced. Thus, the conditions of operation of such apparatus, for the purpose of which they are intended, need not be controlled with any significant restrictions, other than perhaps those dictated by the economics of the operation, in terms of space and energy costs, and in terms of work flow. In the case of an adhesive composition of the type referred to, however, it will be appreciated that two separate but inter-related processes are used in achieving a satisfactory bond, viz. curing and re-activation, and therefore close control is necessary especially during the first stage of the conversion, viz. during curing. The known apparatus referred to is not suitable for achieving such close control.
It is the object of the present invention to provide an apparatus for use in the treatment of articles, e.g. shoe parts, having a coating of a moisture-curable composition, in the operation of which apparatus such coatings can be cured under strictly controlled conditions and at a relatively high rate which is compatible with the flow of work through a factory without giving rise to excessive space demands or storage problems.